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Abstract:

Displaying an image on a display screen is provided by periodically
changing the scanning order in which rows of sub-pixels of the display
screen are scanned. One scanning order can be selected to scan the rows
in the update of a first image frame of the display, and then a different
scanning order can be selected to scan the rows in the update of a second
image frame. Particular scanning orders can be selected in order to
reduce or eliminate the appearance of visual artifacts by changing the
location of the visual artifacts across multiple image frames. For
example, different scanning orders that result in visual artifacts at
different positions on the display screen can be used, and the selection
of scanning order can periodically change among the different scanning
orders such that the position of the visual artifacts changes
periodically during the updating of multiple image frames.

Claims:

1. A method for displaying an image on a display screen, the display
screen including a plurality of lines of sub-pixels, the method
comprising: updating a plurality of consecutive image frames of the
display screen, each image frame being updated by scanning the plurality
of lines of sub-pixels in a selected one of a plurality of different
scanning orders, wherein updating the plurality of consecutive image
frames includes periodically changing the selection of scanning order.

2. The method of claim 1, wherein periodically changing the selection of
scanning order includes changing the selection of scanning order every
consecutive image frame.

3. The method of claim 1, wherein periodically changing the selection of
scanning order includes repetitively alternating the selection between a
first scanning order and a second scanning order.

4. The method of claim 1, wherein scanning the plurality of sub-pixels in
each scanning order includes applying voltages of different polarities in
a corresponding timing pattern of positive and negative changes in
voltage polarity that repeats after the scanning of each of a
corresponding plurality of blocks of adjacent lines of sub-pixels.

5. The method of claim 4, wherein the plurality of different scanning
orders includes a first scanning order and a second scanning order, the
plurality of blocks includes a first block that includes a first sub-set
of lines and a second sub-set of lines, scanning the plurality of lines
of sub-pixels in the first scanning order includes scanning the first
block by scanning the first sub-set of lines before the second sub-set of
lines, and scanning the plurality of lines of sub-pixels in the second
scanning order includes scanning the first block by scanning the second
sub-set of lines before the first sub-set of lines.

6. The method of claim 5, wherein each of the first and second scanning
orders includes a reordered M-line inversion scheme, and the first block
includes 2M lines of sub-pixels.

7. The method of claim 6, wherein the reordered M-line inversion scheme
is a reordered 4-line inversion scheme, the first scanning order is lines
1, 3, 5, and 7 of the first block, and the second scanning order is lines
2, 4, 6, and 8 of the first block.

8. The method of claim 4, wherein the plurality of different scanning
orders includes a first scanning order and a second scanning order,
scanning the plurality of lines of sub-pixels in the first scanning order
includes scanning a first set of adjacent blocks, the lines in each block
in the first set being scanned in a predetermined line order, scanning
the plurality of lines of sub-pixels in the second scanning order
includes scanning a second set of adjacent blocks, the lines in each
block in the second set being scanned in the predetermined line order,
and each block in the second set being shifted by a predetermined number
of lines from a corresponding block in the first set.

9. The method of claim 8, wherein each of the first and second scanning
orders includes a reordered 4-line inversion scheme, and the
predetermined number of lines is five lines.

10. The method of claim 8, wherein the predetermined number of lines is
one line.

11. The method of claim 10, wherein the plurality of different scanning
orders includes 2M different scanning orders, the different scanning
orders including scanning different sets of pluralities of adjacent
blocks of 2M lines of sub-pixels, the lines in each block of 2M lines
being scanned in the predetermined line order, and the blocks in each
different set being shifted by one line from the blocks in at least one
other set.

12. An apparatus comprising: a display screen including a plurality of
lines of sub-pixels; and a scanning system that updates a plurality of
consecutive image frames of the display screen, each image frame being
updated by scanning the plurality of lines of sub-pixels in a selected
one of a plurality of different scanning orders, wherein updating the
plurality of consecutive image frames includes periodically changing the
selection of scanning order.

13. The apparatus of claim 12, wherein periodically changing the
selection of scanning order includes changing the selection of scanning
order every consecutive image frame.

14. The apparatus of claim 12, wherein periodically changing the
selection of scanning order includes repetitively alternating the
selection between a first scanning order and a second scanning order.

15. The apparatus of claim 12, wherein scanning the plurality of
sub-pixels in each scanning order includes applying voltages of different
polarities in a corresponding timing pattern of positive and negative
changes in voltage polarity that repeats after the scanning of each of a
corresponding plurality of blocks of adjacent lines of sub-pixels.

16. The apparatus of claim 15, wherein the plurality of different
scanning orders includes a first scanning order and a second scanning
order, the plurality of blocks includes a first block that includes a
first sub-set of lines and a second sub-set of lines, scanning the
plurality of lines of sub-pixels in the first scanning order includes
scanning the first block by scanning the first sub-set of lines before
the second sub-set of lines, and scanning the plurality of lines of
sub-pixels in the second scanning order includes scanning the first block
by scanning the second sub-set of lines before the first sub-set of
lines.

17. The apparatus of claim 16, wherein each of the first and second
scanning orders includes a reordered M-line inversion scheme, and the
first block includes 2M lines of sub-pixels.

18. The apparatus of claim 17, wherein the reordered M-line inversion
scheme is a reordered 4-line inversion scheme, the first scanning order
is lines 1, 3, 5, and 7 of the first block, and the second scanning order
is lines 2, 4, 6, and 8 of the first block.

19. The apparatus of claim 15, wherein the plurality of different
scanning orders includes a first scanning order and a second scanning
order, scanning the plurality of lines of sub-pixels in the first
scanning order includes scanning a first set of adjacent blocks, the
lines in each block in the first set being scanned in a predetermined
line order, scanning the plurality of lines of sub-pixels in the second
scanning order includes scanning a second set of adjacent blocks, the
lines in each block in the second set being scanned in the predetermined
line order, and each block in the second set being shifted by a
predetermined number of lines from a corresponding block in the first
set.

20. The apparatus of claim 19, wherein each of the first and second
scanning orders includes a reordered 4-line inversion scheme, and the
predetermined number of lines is five lines.

21. The apparatus of claim 19, wherein the predetermined number of lines
is one line.

22. The apparatus of claim 21, wherein the plurality of different
scanning orders includes 2M different scanning orders, the different
scanning orders including scanning different sets of pluralities of
adjacent blocks of 2M lines of sub-pixels, the lines in each block of 2M
lines being scanned in the predetermined line order, and the blocks in
each different set being shifted by one line from the blocks in at least
one other set.

23. A non-transitory computer-readable storage medium storing
computer-readable instructions that, when executed by a computing device,
cause the device to perform a method of displaying an image on a display
screen, the display screen including a plurality of lines of sub-pixels,
the method comprising: updating a plurality of consecutive image frames
of the display screen, each image frame being updated by scanning the
plurality of lines of sub-pixels in a selected one of a plurality of
different scanning orders, wherein updating the plurality of consecutive
image frames includes periodically changing the selection of scanning
order.

24. The non-transitory computer-readable storage medium of claim 23,
wherein periodically changing the selection of scanning order includes
changing the selection of scanning order every consecutive image frame.

25. The non-transitory computer-readable storage medium of claim 23,
wherein periodically changing the selection of scanning order includes
repetitively alternating the selection between a first scanning order and
a second scanning order.

Description:

FIELD OF THE DISCLOSURE

[0001] This relates generally to scanning lines of sub-pixels of a display
in a scanning order, and more particularly, to changing the scanning
order from one frame to another.

BACKGROUND OF THE DISCLOSURE

[0002] Display screens of various types of technologies, such as liquid
crystal displays (LCDs), organic light emitting diode (OLED) displays,
etc., can be used as screens or displays for a wide variety of electronic
devices, including such consumer electronics as televisions, computers,
and handheld devices (e.g., cellular telephones, audio and video players,
gaming systems, and so forth). LCD devices, for example, typically
provide a flat display in a relatively thin package that is suitable for
use in a variety of electronic goods. In addition, LCD devices typically
use less power than comparable display technologies, making them suitable
for use in battery-powered devices or in other contexts where it is
desirable to minimize power usage.

[0003] LCD devices typically include multiple picture elements (pixels)
arranged in a matrix. The pixels may be driven by scanning line and data
line circuitry to display an image on the display that can be
periodically refreshed over multiple image frames such that a continuous
image may be perceived by a user. Individual pixels of an LCD device can
permit a variable amount light from a backlight to pass through the pixel
based on the strength of an electric field applied to the liquid crystal
material of the pixel. The electric field can be generated by a
difference in potential of two electrodes, a common electrode and a pixel
electrode. In some LCDs, such as electrically-controlled birefringence
(ECB) LCDs, the liquid crystal can be in between the two electrodes. In
other LCDs, such as in-plane switching (IPS) and fringe-field switching
(FFS) LCDs, the two electrodes can be positioned on the same side of the
liquid crystal. In many displays, the direction of the electric field
generated by the two electrodes can be reversed periodically. For
example, LCD displays can scan the pixels using various inversion
schemes, in which the polarities of the voltages applied to the common
electrodes and the pixel electrodes can be periodically switched, i.e.,
from positive to negative, or from negative to positive. As a result, the
polarities of the voltages applied to various lines in a display panel,
such as data lines used to charge the pixel electrodes to a target
voltage, can be periodically switched according to the particular
inversion scheme.

SUMMARY

[0004] The following description includes examples of displaying an image
on a display screen by periodically changing the scanning order in which
rows of sub-pixels of the display screen are scanned. For example, one
scanning order can be selected to scan the rows in the update of a first
image frame of the display, and then a different scanning order can be
selected to scan the rows in the update of a second image frame. In some
embodiments, particular scanning orders can be selected in order to
reduce or eliminate the appearance of visual artifacts by changing the
location of the visual artifacts across multiple image frames. For
example, different scanning orders that result in visual artifacts at
different positions on the display screen can be used, and the selection
of scanning order can periodically change among the different scanning
orders such that the position of the visual artifacts changes
periodically during the updating of multiple image frames.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] FIGS. 1A-1D illustrate an example mobile telephone, an example
media player, an example personal computer, and an example display that
each include an example display screen that can be scanned according to
embodiments of the disclosure.

[0009] FIG. 5 illustrates an example scanning order according to
embodiments of the disclosure.

[0010]FIG. 6 illustrates another example scanning order according to
embodiments of the disclosure.

[0011] FIG. 7 illustrates an example method of periodically changing the
selection of scanning order according to various embodiments.

[0012] FIG. 8 illustrates another example method of periodically changing
the selection of scanning order according to various embodiments.

[0013] FIG. 9 illustrates another example method of periodically changing
the selection of scanning order according to various embodiments.

[0014] FIG. 10 illustrates example display that each include another
example display screen that can be scanned according to embodiments of
the disclosure.

[0015] FIG. 11 illustrates reduction of additional visual artifacts using
the example method of periodically changing the selection of scanning
order of FIG. 9 according to various embodiments.

[0016] FIG. 12 is a block diagram of an example computing system that
illustrates one implementation of an example scanning system of a display
screen according to embodiments of the disclosure.

DETAILED DESCRIPTION

[0017] In the following description of example embodiments, reference is
made to the accompanying drawings which form a part hereof, and in which
it is shown by way of illustration specific embodiments in which
embodiments of the disclosure can be practiced. It is to be understood
that other embodiments can be used and structural changes can be made
without departing from the scope of the embodiments of this disclosure.

[0018] The following description includes examples of displaying an image
on a display screen by periodically changing the scanning order in which
rows of sub-pixels of the display screen are scanned. For example, one
scanning order can be selected to scan the rows in the update of a first
image frame of the display, and then a different scanning order can be
selected to scan the rows in the update of a second image frame. In some
embodiments, particular scanning orders can be selected in order to
reduce or eliminate the appearance of visual artifacts by changing the
location of the visual artifacts across multiple image frames. For
example, different scanning orders that result in visual artifacts at
different positions on the display screen can be used, and the selection
of scanning order can periodically change among the different scanning
orders such that the position of the visual artifacts changes
periodically during the updating of multiple image frames.

[0019] FIGS. 1A-1D show example systems that can include display screens
that can be scanned according to embodiments of the disclosure. FIG. 1A
illustrates an example mobile telephone 136 that includes a display
screen 124. FIG. 1B illustrates an example digital media player 140 that
includes a display screen 126. FIG. 1c illustrates an example personal
computer 144 that includes a display screen 128. FIG. 1D illustrates an
example display screen 150, such as a stand-alone display. In some
embodiments, display screens 124, 126, 128, and 150 can be touch screens
that include touch sensing circuitry. In some embodiments, touch sensing
circuitry can be integrated into the display pixels.

[0020]FIG. 1D illustrates some details of example display screen 150.
FIG. 1D includes a magnified view of display screen 150 that shows
multiple display pixels 153, each of which can include multiple display
sub-pixels, such as red (R), green (G), and blue (B) sub-pixels in an RGB
display. Although various embodiments are described with respect to
display pixels, one skilled in the art would understand that the term
display pixels (or simply "pixels") can be used interchangeably with the
term display sub-pixels (or simply "sub-pixels") in embodiments in which
display pixels include multiple sub-pixels. For example, some embodiments
directed to RGB displays can include display pixels divided into red,
green, and blue sub-pixels. In other words, each sub-pixel can be a red
(R), green (G), or blue (B) sub-pixel, with the combination of all three
R, G, and B sub-pixels forming one display pixel.

[0021] Data lines 155 can run vertically through display screen 150, such
that each display pixel in a column of display pixels can include a set
156 of three data lines (an R data line, a G data line, and a B data
line) corresponding to the three sub-pixels of each display pixel. In
some embodiments, each data line 155 in set 156 can be operated
concurrently during the update of a corresponding sub-pixel. For example,
a display driver can apply the target voltages of data lines 155
concurrently to the data lines in set 156 to update the sub-pixels of a
display pixel. In some embodiments, the three data lines in each display
pixel can be operated sequentially. For example, a display driver can
multiplex an R data voltage, a G data voltage, and a B data voltage onto
a single bus line, and then a demultiplexer in the border region of the
display can demultiplex the R, G, and B data voltages to apply the data
voltages to the corresponding data lines in the particular sequence.

[0022]FIG. 1D also includes a magnified view of two of the display pixels
153, which illustrates that each display pixel can include pixel
electrodes 157, each of which can correspond to one of the sub-pixels,
for example. Each display pixel can include a common electrode (Vcom) 159
that can be used in conjunction with pixel electrodes 157 to create an
electrical potential across a pixel material (not shown). Varying the
electrical potential across the pixel material can correspondingly vary
an amount of light emanating from the sub-pixel. In some embodiments, for
example, the pixel material can be liquid crystal. A common electrode
voltage can be applied to a Vcom 159 of a display pixel, and a data
voltage can be applied to a pixel electrode 157 of a sub-pixel of the
display pixel through the corresponding data line 155. A voltage
difference between the common electrode voltage applied to Vcom 159 and
the data voltage applied to pixel electrode 157 can create the electrical
potential across the liquid crystal of the sub-pixel. The electrical
potential between Vcom 159 and pixel electrode 157 can generate an
electric field through the liquid crystal, which can cause inclination of
the liquid crystal molecules to allow polarized light from a backlight
(not shown) to emanate from the sub-pixel with a luminance that depends
on the strength of the electric field (which can depend on the voltage
difference between the applied common electrode voltage and data
voltage). In other embodiments, the pixel material can include, for
example, a light-emitting material, such as can be used in organic light
emitting diode (OLED) displays.

[0023] In some scanning methods, the direction of the electric field
across the pixel material can be reversed periodically. In LCD displays,
for example, periodically switching the direction of the electric field
can help prevent the molecules of liquid crystal from becoming stuck in
one direction. Switching the electric field direction can be accomplished
by reversing the polarity of the electrical potential between the pixel
electrode and the Vcom. In other words, a positive potential from the
pixel electrode to the Vcom can generate an electric field across the
liquid crystal in one direction, and a negative potential from the pixel
electrode to the Vcom can generate an electric field across the liquid
crystal in the opposite direction. In some scanning methods, switching
the polarity of the potential between the pixel electrode and the Vcom
can be accomplished by switching the polarities of the voltages applied
to the pixel electrode and the Vcom. For example, during an update of an
image in one frame, a positive voltage can be applied to the pixel
electrode and a negative voltage can be applied to the Vcom. In a next
frame, a negative voltage can be applied to the pixel electrode and a
positive voltage can be applied to the Vcom. One skilled in the art would
understand that switching the polarity of the potential between the pixel
electrode and the Vcom can be accomplished without switching the polarity
of the voltage applied to either or both of the pixel electrode and Vcom.
In this regard, although example embodiments are described herein as
switching the polarity of voltages applied to data lines, and
correspondingly, to pixel electrodes, it should be understood that
reference to positive/negative voltage polarities can represent relative
voltage values. For example, an application of a negative polarity
voltage to a data line, as described herein, can refer to application of
a voltage with a positive absolute value (e.g., +1V) to the data line,
while a higher voltage is being applied to the Vcom, for example. In
other words, in some cases, a negative polarity potential can be created
between the pixel electrode and the Vcom by applied positive (absolute
value) voltages to both the pixel electrode and the Vcom, for example.

[0024] The brightness (or luminance) of the corresponding pixel or
sub-pixel depends on the magnitude of the difference between the pixel
electrode voltage and the Vcom voltage. For example, the magnitude of the
difference between a pixel electrode voltage of +2V and a Vcom voltage of
-3V is 5V. Likewise, the magnitude of the difference between a pixel
electrode voltage of -2V and a Vcom voltage of +3V is also 5V. Therefore,
in this example, switching the polarities of the pixel electrode and Vcom
voltages from one frame to the next would not change the brightness of
the pixel or sub-pixel.

[0025] Various inversion schemes can be used to periodically switch the
polarities of the pixel electrodes and the Vcoms. In a single line
inversion scheme, for example, when the scanning of a first frame is
completed, the location of the positive and negative polarities on the
pixel electrodes can be in a pattern of rows of the display that
alternates every single row, e.g., the first row at the top of the
display screen having positive polarities, the second row from the top
having negative polarities, the third row from the top having positive
polarities, etc. In a subsequent frame, such as the second frame, the
pattern of voltage polarities can be reversed, e.g., the first row with
negative polarities, the second row with positive polarities, etc.

[0026] During the scanning operation in single line inversion, the rows
can be updated in a scanning order that is the same as the order of the
position of the rows from a first row at the top of the display screen to
a last row at the bottom of the display screen. For example, the first
row at the top of the display can be updated first, then the second row
from the top can be updated second, then the third row from the top can
be updated third, etc. In this way, there can be a repeating timing
pattern of voltage polarity swings on the data lines during the scanning
operation. In other words, repeatedly switching the voltages on the data
lines from positive to negative to positive to negative, etc., during the
scanning operation results in a repeating timing pattern of positive and
negative voltage swings. In single line inversion, for example, there is
one positive voltage swing after one row is updated, and one negative
voltage swing after the next row in the scanning order is updated. Thus,
the timing pattern of positive/negative voltage swings repeats after the
updating of each block of two adjacent rows in single line inversion.

[0027] In some line inversion schemes, the location of the positive and
negative polarities on the pixel electrodes can be in a pattern of rows
of the display that alternates every two rows (for 2-line inversion),
every three rows (for 3-line inversion), every four rows (for 4-line
inversion), etc. In a 2-line inversion scheme, for example, when the
scanning of a first frame is completed, the location of the positive and
negative polarities on the pixel electrodes can be in a pattern of rows
of the display that alternates every two rows, e.g., the first and second
rows at the top of the display screen having positive polarities, the
third and fourth rows from the top having negative polarities, the fifth
and sixth rows from the top having positive polarities, etc. In a
subsequent frame, such as the second frame, the pattern of voltage
polarities can be reversed, e.g., the first and second rows with negative
polarities, the third and fourth rows with positive polarities, etc. In
general, the location of positive and negative polarities on the pixel
electrodes in an M-line inversion scheme can alternate every M rows.

[0028] Voltage swings on the data lines in an M-line inversion scheme can
repeat every 2M rows. In other words, there is one positive voltage swing
after M rows are updated, and one negative voltage swing after the next M
rows in the scanning order are updated. Thus, the timing pattern of
positive and negative changes in voltage polarity repeats after the
scanning of each block of 2M adjacent rows in M-line inversion.

[0029] In a reordered M-line inversion scheme, the location of the
resulting pattern of alternating positive and negative polarities on the
pixel electrodes can be the same pattern as in regular single line
inversion described above, i.e., alternating polarity every single row.
However, while the regular line inversion schemes described above can
update the rows in the sequential order of row position, in a reordered
line inversion scheme, the rows can be updated in an order that is not
sequential. In one example reordered 4-line inversion scheme, the
scanning order can update four rows in a block of eight rows with
positive polarity and update the other four rows in the block with
negative polarity. However, unlike regular 4-line inversion, the scanning
order of reordered 4-line inversion can update, for example, update rows
1, 3, 5, and 7 with positive polarity voltages, and then update rows 2,
4, 6, and 8 with negative polarity voltages. Therefore, in this example
reordered 4-line inversion scheme, the timing pattern of
positive/negative voltage swings can repeat after the updating of 8 rows
(i.e., after the updating of 2M rows for a reordered M-line inversion
scheme), which is similar to regular 4-line inversion. However, the
pattern of the location of alternating positive and negative pixel
electrodes can repeat every single row, which is similar to regular
single line inversion. In this way, for example, reordered line inversion
schemes can reduce the number of voltage polarity swings on the data
lines during the scanning of a single frame, while maintaining a
row-by-row location of alternating polarities. In the context of this
document, in a reordered M-line inversion scheme, M is an integer greater
than one.

[0030] Thus, the particular order and location in which voltages of
different polarities are applied to the pixel electrodes of sub-pixels of
a display can depend on the particular inversion scheme being used to
scan the display.

[0031] As will be described in more detail below with respect to various
example embodiments, applying a voltage to a sub-pixel in one row of
pixels can affect the voltages of sub-pixels in other rows of pixels. For
example, a capacitance that can exist between pixel electrodes can allow
a large voltage swing (for example, from a positive polarity voltage to a
negative polarity voltage, or vice-versa) on the pixel electrode of one
sub-pixel (which may be referred to herein as an "aggressor sub-pixel,"
or simply an "aggressor pixel") to be coupled into a pixel electrode in
an adjacent row, which can result in a change in the voltage of the pixel
electrode in the adjacent row. The change in the voltage of the pixel
electrode in the adjacent row can cause an erroneous increase or decrease
in the brightness of the sub-pixel (which may be referred to herein as a
"victim sub-pixel," or simply a "victim pixel") with the affected pixel
electrode. In some cases, the erroneous increase or decrease in victim
pixel brightness can be detectable as a visual artifact in the displayed
image. As will be apparent from the description below, some sub-pixels
can be an aggressor during the update of the sub-pixel's row and can be a
victim during the update of another row.

[0032] FIG. 2 illustrates an example arrangement of pixel electrodes 201
in an example display screen 200. Pixel electrodes 201 can have an
arrangement similar to pixel electrodes 157 in FIG. 1D, for example, in
which the pixel electrodes can be arranged in horizontal lines, such as
rows 203. For the purpose of clarity other pixel electrodes in rows 203
of display screen 200 are not shown in this figure. Pixel electrodes 201
shown in FIG. 2 can each be associated with a data line 205, such as data
line 155 in FIG. 1D. Each pixel TFT 207 can include a source 209
connected to data line 205, a gate 211, and a drain 213 connected to
pixel electrode 201. Each pixel TFT 207 in one row 203 of pixels can be
switched on by applying an appropriate gate line voltage to a gate line
215 corresponding to the row. During a scanning operation of display
screen 200, a target voltage of each pixel electrode 201 in one row 203
can be applied individually to the pixel electrode by switching on pixel
TFTs 207 of the of the row with the corresponding gate line 215 while the
target voltages of each pixel electrode in the row are being applied to
data lines 205.

[0033] To update all of the pixel electrodes 201 in display screen 200,
thus refreshing an image frame displayed by the sub-pixels of the display
screen, rows 203 can be scanned by applying the appropriate gate line
voltages to gate lines 215 in a particular scanning order. For example, a
scanning order can be sequential in order of position of rows 203 from a
first row at the top of display screen 200 to a last row at the bottom of
the display screen. In other words, the first row of the display can be
scanned first, then the next adjacent row (i.e., the second row) can be
scanned next, then the next adjacent row (i.e., the third row) can be
scanned, etc. One skilled in the art would understand that other scanning
orders can be used.

[0034] When a particular row 203 is being scanned to update the voltages
on pixel electrodes 201 of the row with the target data voltages being
applied to the data lines 205 during the scanning of the row, pixel TFTs
207 of the other rows can be switched off so that the pixel electrodes in
the rows that are not being scanned remain disconnected from the data
lines. In this way, data voltages on the data lines can be applied to a
single row currently being scanned, while the voltages on the data lines
are not applied directly to the pixel electrodes in the other rows.

[0035] However, updating the voltages of the pixel electrodes 201 of a
particular row 203 can have an effect on the voltages of pixel electrodes
in other rows. For example, a pixel-to-pixel capacitance 217 existing
between adjacent pixel electrodes 201, for example, can allow voltage
changes in one pixel electrode to affect the voltage values of adjacent
pixel electrodes through a capacitance coupling between the pixel
electrodes.

[0036]FIG. 3 illustrates an example scanning operation in which rows can
be scanned in a line-by-line sequential order. The inversion scheme shown
in FIG. 3 can be, for example, single line inversion (or single dot
inversion). The voltages on pixel electrodes 301a-d of four rows 303 are
represented by voltage graphs next to each pixel electrode, which show
the voltage on the pixel electrode during scanning of various rows. At
the beginning of the frame, pixel electrode 301a of row 1 can have a
positive voltage, pixel electrode 301b of row 2 can have a negative
voltage, pixel electrode 301c of row 3 can have a positive voltage, and
pixel electrode 301d of row 4 can have a negative voltage. The voltages
at the beginning of the frame can be, for example, the target voltages
that were applied to the pixels during the previous frame. In other
words, the voltages of the pixel electrodes 301a-d at the beginning of
the frame can be the voltages used to display the image of the previous
frame. In this example, the polarity of the voltages on the pixel
electrodes 301a-d can be changed for each scan line (e.g., single line
inversion or single dot inversion). FIG. 3 shows a scan of row 1, during
which a pixel TFT 305 of a pixel electrode 301a of row 1 can be switched
on by applying the appropriate gate line voltage to a gate line 307.
During the scan of row 1, a negative voltage can be applied to a data
line 309 to update the voltage on the pixel electrode of row 1 as shown
in the voltage graph next to the pixel electrode. The voltage graph of
pixel electrode 301a during the scan of row 1 shows a voltage swing from
positive voltage to negative voltage, which is represented in the voltage
graph by a large down arrow. Due to effects such as the capacitance
coupling described above, for example, the large negative voltage swing
of pixel electrode 301a can cause a corresponding negative voltage swing
in adjacent pixel electrodes such as pixel electrode 301b. This effect on
the voltages on adjacent pixel electrodes can be significantly smaller in
magnitude, therefore, the voltage graph of pixel electrode 301b shows a
slight negative change, which is represented in the voltage graph by a
small down arrow, during the scan of row 1. As described above, the
luminance of the sub-pixel associated with a pixel electrode can depend
on the magnitude of the pixel voltage. The negative voltage change in
pixel electrode 301b caused by the large negative voltage swing in pixel
electrode 301a can increase the magnitude of the voltage of pixel
electrode 301b. Therefore, the effect of the negative voltage swing on
pixel electrode 301a can be an increase in the luminance, e.g.,
brightness, of the sub-pixel of pixel electrode 301b. The increase in
brightness sub-pixel of pixel electrode 301b is represented in FIG. 3 by
hatch marks surrounding pixel electrode 301b.

[0037] In the scan of row 2, pixel TFT 305 of pixel electrode 301b can be
switched on with a gate line voltage applied to the corresponding gate
line 307, while the pixel TFTs of the other rows can remain off. While
pixel electrode 301b is connected to data line 309 during the scan of row
2, a positive target voltage can be applied to the data line to update
the voltage of pixel electrode 301b. The voltage graph of pixel electrode
301b illustrates that the application of the positive voltage causes a
large positive voltage swing on pixel electrode 301b, which is
represented by the large up arrow in the voltage graph. A large positive
swing in voltage on pixel electrode 301b can affect the voltages of
adjacent pixel electrodes 301a and 301c correspondingly, resulting in
relatively smaller positive changes in voltage on the two adjacent pixel
electrodes. The smaller positive voltage swings in the adjacent pixel
electrodes are represented in the corresponding voltage graphs by small
up arrows. The positive voltage change on pixel electrode 301a can cause
the negative voltage on the pixel electrode to be reduced in magnitude,
which can result in decrease in the brightness of the sub-pixel of pixel
electrode 301a. In other words, the brightness of the sub-pixel of pixel
electrode 301a can be reduced such that the sub-pixel appears darker,
which is represented in FIG. 3 by the thicker, dark borders shown on
pixel electrode 301a in the scan of row 2.

[0038] The large positive voltage swing on pixel electrode 301b can result
in an increase in the brightness of the sub-pixel of pixel electrode 301c
because the positive change to the voltage on pixel electrode 301c can
increase the magnitude of the voltage on pixel electrode 301c. The
increase in brightness of pixel electrode 301c is represented in FIG. 3
by hatch marks surrounding pixel electrode 301c.

[0039] In the scan of row 2, the application of the target voltage to
pixel electrode 301b can correct, or overwrite, the erroneous increase in
brightness introduced previously. For example, in the scan of row 1, the
brightness of the sub-pixel of pixel electrode 301b was increased, making
the sub-pixel appear brighter, due to the voltage swing occurring on
pixel electrode 301a. While this increased brightness of pixel electrode
301b might otherwise be visible as a display artifact, in this case, the
erroneous increase in brightness can be quickly overwritten in the scan
of row 2, which immediately follows the scan of row 1. In other words, in
the scan of row 2, the voltage on pixel electrode 301b is updated to the
target voltage for the sub-pixel regardless of whether the pixel
electrode 301b is being update from a correct voltage (i.e., the target
voltage from the previous frame) or updated from an incorrect voltage
(e.g., an erroneously higher or lower voltage). Therefore, pixel
electrode 301b is shown during the scan of row 2 in FIG. 3 with the hatch
marks removed. In other words, the scan of row 2 can overwrite the
erroneous voltage on pixel electrode 301b with the current target
voltage.

[0040] During a scan of row 3, pixel TFT 305 corresponding to pixel
electrode 301c can be switched on, as described above. A negative target
voltage can be applied to data line 309, which can cause the voltage on
pixel electrode 301c to swing from positive to negative as represented by
the large down arrow in the voltage graph. The negative swing in voltage
on pixel electrode 301c can cause negative voltage changes on pixel
electrodes 301b and 301d, causing a decrease in the magnitude of the
positive voltage on pixel electrode 301b and an increase in magnitude of
the voltage on pixel electrode 301d. Thus, as before, updating the
voltage on pixel electrode 301c can affect adjacent sub-pixels by causing
the sub-pixel of pixel electrode 301b to appear darker and the sub-pixel
of pixel electrode 301d to appear brighter.

[0041]FIG. 4 shows another representation of the example scanning
operation shown in FIG. 3. Specifically, FIG. 4 illustrates a simplified
notation for describing various effects on sub-pixel brightness that can
occur during scanning operations. The notation illustrated in FIG. 4 will
be adopted below in the descriptions of additional example embodiments
shown in FIGS. 5, 7, and 9-11.

[0042]FIG. 4 illustrates rows 303 including sub-pixels 401 corresponding
to the sub-pixels of pixel electrodes 301a-d of FIG. 3. Sub-pixel voltage
polarities 403 associated with each sub-pixel 401 are shown in FIG. 4.
The sub-pixel voltage polarities 403 correspond to the polarities of the
voltages on pixel electrodes 301a-d shown in FIG. 3. FIG. 4 illustrates
the voltage polarities 403 on the sub-pixels 401 of rows 1-4 at the
beginning of the frame, corresponding to FIG. 3. As described above,
during the update of row 1, a target voltage is applied to the pixel
electrode (i.e., pixel electrode 301a) of sub-pixel 401 in row 1. The
direct application of voltage to a pixel electrode is illustrated in the
figures with the notation of a circle around the polarity sign of the
applied voltage in the sub-pixel. A large voltage swing on a pixel
electrode of a sub-pixel due to a direct application of voltage to the
pixel electrode is illustrated in the figures with the notation of a
large up-arrow, corresponding to a positive voltage swing, or a large
down-arrow, corresponding to a negative voltage swing, in the sub-pixel.

[0043] In the update of row 1 shown in FIG. 4, for example, the negative
target voltage applied to sub-pixel 401 of row 1 can cause a negative
voltage swing because the sub-pixel voltage polarity 403 of the sub-pixel
was positive at the beginning of the update of row 1, e.g., at the
beginning of the frame. As described above, the negative voltage swing
can cause a corresponding negative voltage change on sub-pixel 401 of row
2, which is illustrated in the figures with the notation of a small
down-arrow (or a small up-arrow for positive voltage changes). Also as
described above, the negative voltage change can cause sub-pixel 401 of
row 2 to appear brighter, which is illustrated in the figures with the
notation of dashed lines used for the left and right borders of the
sub-pixel.

[0044] In the update of row 2 shown in FIG. 4, a positive polarity target
voltage can be applied to sub-pixel 401 of row 2, which can cause a large
positive voltage swing on the sub-pixel. As described above, sub-pixel
401 of row 1 can be affected by becoming darker due to the corresponding
positive voltage change to the negative polarity voltage on the sub-pixel
of row 1. The decrease in brightness, e.g., darker appearance, of
sub-pixel 401 of row 1 is illustrated in the figures with the notation of
thick, dark lines used for the left and right borders of the sub-pixel.
As described above, sub-pixel 401 of row 3 can appear brighter due to the
positive voltage change caused by the voltage swing on the pixel
electrode (i.e., pixel electrode 301b) of sub-pixel 401 of row 2. Thus,
the left and right borders of sub-pixel 401 of row 3 are shown as dashed
lines in FIG. 4. The update of row 3 shown in FIG. 4 likewise represents
the above-described update of row 3, including the application of
negative polarity target voltage to sub-pixel 401 of row 3, a large
negative swing on the corresponding pixel electrode, and a resulting
decrease and increase in the brightness of the sub-pixels of row 2 and
row 4, respectively.

[0045]FIG. 4 also illustrates the update of row 4, in which the change in
polarity of sub-pixel 401 of row 4 can result in a decrease in the
brightness of the preceding sub-pixel of row 3, and an increase in the
brightness of the next sub-pixel of row 5 (not shown). Thus, it can be
seen from FIG. 4 that the scanning of each row under the particular
inversion scheme of the present example, i.e., single line inversion (or
single dot inversion), can result in a decrease in brightness of the
sub-pixels in preceding rows and an increase in brightness of the
sub-pixels in the next rows. However, the increase in brightness of the
next row can be subsequently overwritten in the next scan step, leaving
only the decreases in brightness of each sub-pixel of the display.

[0046] A uniform decrease (or increase) in brightness of all sub-pixels
may not be detectable as a visual artifact. In other words, the
particular order of scanning in some types of inversion schemes may mask
the effects of pixel-to-pixel coupling on sub-pixel luminance. On the
other hand, some types of inversion schemes may exacerbate visual
artifacts that can result from pixel-to-pixel coupling.

[0047] FIG. 5 illustrates an example scanning operation to update a first
image frame of a display using an example scanning order including a
reordered 4-line inversion scheme according to various embodiments. The
example scanning operation shown in FIG. 5 can result in erroneous
changes in the brightness of some sub-pixels, but not other sub-pixels in
the first frame. In this example scanning operation, the changes in
brightness can include decreases in brightness. The unaffected sub-pixels
and the darker sub-pixels can create a pattern of different brightness
levels on the display screen, which may be detectable as a visual
artifact if the pattern persists through multiple frame updates of the
display. As will be described in more detail below in reference to FIG.
6, updating the display using a different scanning order of the reordered
4-line inversion scheme can change the pattern of different brightness
levels on the display screen from the pattern in the first frame. As will
be described in more detail below in reference to FIG. 7, periodically
changing the pattern of different brightness levels appearing in frames
by scanning the display using different scanning orders in different
frames can disrupt the persistence of one particular pattern, which can
reduce or eliminate the perception of a visual artifact.

[0048] In the example of FIG. 5, the display can be updated in a first
frame using a first scanning order including a reordered 4-line inversion
scheme. FIG. 5 shows the complete scanning of a block of eight rows of
the reordered 4-line inversion scheme, i.e., block 2, which includes rows
9-16. FIG. 5 also illustrates the updating of an adjacent row above block
2 (i.e., row 8), which is the last row in block 1, and the updating of an
adjacent row after block 2 (i.e., row 17), which is the first row in
block 3. Because FIG. 5 illustrates the updating of multiple rows over
the course of the scanning operation, for the sake of clarity FIG. 5 (and
other figures herein) shows only one sub-pixel per row. The
representative sub-pixel of a particular row shown in the figures may be
referred to by the row number in which the sub-pixel is located (e.g.,
the illustrated sub-pixel in row 9 may be referred to herein simply as
sub-pixel 9). However, it is understood that each row can include
multiple sub-pixels. It is further understood that the other sub-pixels
in each row can have the same and/or different polarities as the polarity
of the representative sub-pixel, depending on the particular inversion
scheme being used, such as dot inversion, line inversion, etc.

[0049] At the beginning of the first frame, the voltage polarities of the
sub-pixels in the first, third, fifth, and seventh rows of block 2 (i.e.,
sub-pixels 9, 11, 13, and 15) can be negative, and the voltage polarities
of the sub-pixels in the second, fourth, sixth, and eighth rows of block
2 (i.e., sub-pixels 10, 12, 14, and 16) can be positive. In this example
first scanning order of the reordered 4-line inversion scheme, each block
can be scanned in a particular line order in which a first sub-set of
rows in each block is scanned first, and then a second sub-set of rows of
the block is scanned next. In the example of FIG. 5, each block can be
scanned in the following line order within the block: first row, third
row, fifth row, seventh row, second row, fourth row, sixth row, eighth
row (1st, 3rd, 5th, 7th, 2nd, 4th, 6th, 8th). Thus, the first sub-set of
rows can be rows 1, 3, 5, and 7 (which can be scanned in that order), and
the second sub-set of rows can be rows 2, 4, 6, and 8 (which can be
scanned in that order), in this example.

[0050] Scanning of the display in the first frame can begin with the
update of the first row in the block 1 (i.e., row 1, not shown) and
continue with the scanning of rows 3, 5, 7, 2, 4, and 6 (not shown),
until scanning reaches row 8. FIG. 5 illustrates the scanning of row 8,
during which a negative voltage can be applied to the pixel electrode of
sub-pixel 8 to update the sub-pixel to its target voltage for the first
frame. Updating sub-pixel 8 can result in a large negative swing in
voltage, which can cause a corresponding negative change to the negative
voltage of the sub-pixel of row 9 (i.e., sub-pixel 9), resulting in an
increase in the brightness of sub-pixel 9. After the updating of row 8,
the scanning of block 1 can be complete.

[0051] The scanning of block 2 can begin with updating of row 9 (i.e., the
1st row of block 2) with a positive target voltage, which can cause a
positive voltage change affecting the adjacent sub-pixels with a positive
change to the negative voltage of sub-pixel 8 and the positive voltage of
sub-pixel 10, resulting in a decrease in brightness of sub-pixel 8 and an
increase in brightness of sub-pixel 10. Scanning block 2 can continue
with the updating of sub-pixel 11, which can result in a further increase
in the brightness of sub-pixel 10. A new notation is introduced in FIG. 5
to represent a further increase in brightness of a sub-pixel, i.e., in
the case that an erroneous increase in brightness of a victim sub-pixel
occurs twice. The further increase in the brightness of sub-pixel 10 is
represented by the removal of the left and right borders of the
sub-pixel.

[0052] The updating of sub-pixel 11 also can result in an increase in the
brightness of sub-pixel 12. The scanning of block 2 can continue with the
updating of sub-pixels, 13, 15, 10, 12, 14, and 16, as shown in FIG. 5.
In some cases during the scanning of block 2, the brightness of a victim
sub-pixel can be decreased twice, i.e., by two aggressor sub-pixels. For
example, the brightness of sub-pixel 11 can be decreased during the
updating of sub-pixel 10. Then, during the updating of sub-pixel 12, the
brightness of sub-pixel 11 can be further decreased. The further decrease
in brightness is represented in the figures by a new notation of thicker,
dark lines used for the left, right, top, and bottom borders of the
sub-pixel. After the updating of row 16, the scanning of block 2 can be
complete.

[0053] FIG. 5 also shows the updating of the first row in block 3, i.e.,
sub-pixel 17, to illustrate the final effects in block 2 of
pixel-to-pixel coupling of voltage swings from aggressor sub-pixels to
victim sub-pixels after the update of row 17 is completed, e.g., as shown
during the update of row 21, for example, in the first frame using the
first scanning order. In particular, sub-pixels 9 and 16 can have
decreased brightness, sub-pixels 10, 12, and 14 can have no errors in
brightness, and sub-pixels 11, 13, and 15 can have further decreased
brightness. If this pattern of erroneous brightness persisted over
multiple frames, the pattern might be observable as a visual artifact.

[0054]FIG. 6 illustrates an example scanning operation to update a
subsequent image frame of the display, such as a second frame, using an
example scanning order that can be different than the scanning order used
in the first frame according to various embodiments. The example scanning
operation shown in FIG. 6 can result in erroneous changes in the
brightness of some sub-pixels, but not other sub-pixels in the second
frame. Like the scanning operation of FIG. 5, the unaffected sub-pixels
and the darker sub-pixels resulting from the scanning operation of FIG. 6
can create a pattern of different brightness levels on the display
screen, which may be detectable as a visual artifact if the pattern
persists over multiple frame updates of the display. However, as will now
be described, the pattern resulting from the scanning operation of FIG. 6
can be different than the pattern resulting from the scanning operation
of FIG. 5.

[0055] In the example of FIG. 6, the display can be scanned in the second
frame using an example second scanning order of the reordered 4-line
inversion scheme. Like the example illustrated in FIG. 5, the example of
FIG. 6 shows the complete scanning of block 2 (i.e., the updating of rows
9-16) and the updating of rows 8 and 17 in the second frame.

[0056] At the beginning of the second frame, the voltage polarities of the
sub-pixels in the first, third, fifth, and seventh rows of block 2 (i.e.,
sub-pixels 9, 11, 13, and 15) can be positive, and the voltage polarities
of the sub-pixels in the second, fourth, sixth, and eighth rows of block
2 (i.e., sub-pixels 10, 12, 14, and 16) can be negative. In this example
second scanning order of the reordered 4-line inversion scheme, each
block can be scanned in the following order of rows: second row, fourth
row, sixth row, eighth row, first row, third row, fifth row, seventh row
(2nd, 4th, 6th, 8th, 1st, 3rd, 5th, 7th). In other words, the second
scanning order can scan each block using a different line order within
the block than the line order used by the first scanning order shown in
FIG. 5. In particular, the second scanning order can scan each block by
first scanning the second sub-set of rows (i.e., rows 2, 4, 6, and 8),
and next scanning the first sub-set of rows (i.e., rows 1, 3, 5, and 7).

[0057] Scanning of the display in the second frame can begin with the
update of the second row in the block 1 (i.e., row 2, not shown) and
continue with the scanning of rows 4 and 6, until the scanning reaches
row 8. FIG. 6 illustrates the scanning of row 8, during which a positive
voltage can be applied to the pixel electrode of sub-pixel 8 to update
the sub-pixel to its target voltage for the second frame. Updating
sub-pixel 8 can result in a large positive swing in voltage, which can
cause a corresponding positive change to the positive voltage of the
sub-pixel of row 9 (i.e., sub-pixel 9), resulting in an increase in the
brightness of sub-pixel 9. Scanning of the first block can continue with
the scanning of rows 1, 3, 5, and 7 (not shown), at which point the
scanning of block 1 can be complete.

[0058] The scanning of block 2 can begin with updating of row 10 with a
positive target voltage, which can cause a positive voltage change
affecting the adjacent sub-pixels with a positive change to the positive
voltage of sub-pixel 9 and the positive voltage of sub-pixel 11,
resulting in an increase in a further increase in the brightness of
sub-pixel 9 and an increase in the brightness of sub-pixel 11. Scanning
block 2 can continue with the updating of sub-pixel 12, which can result
in a further increase in the brightness of sub-pixel 11 and an increase
in the brightness of sub-pixel 13. The scanning of block 2 can continue
with the updating of sub-pixels, 14, 16, 9, 11, 13, and 15, as shown in
FIG. 6. After the updating of row 15, the scanning of block 2 can be
complete.

[0059]FIG. 6 also shows the updating of the first row in block 3, i.e.,
sub-pixel 17, to illustrate the final effects in block 2 of
pixel-to-pixel coupling of voltage swings from aggressor sub-pixels to
victim sub-pixels after the update of row 17 is completed, e.g., as shown
during the update of row 19, for example, in the second frame using the
second scanning order. In particular, sub-pixels 10, 12, 14, and 16 can
have two decreases in brightness, and sub-pixels 9, 11, 13, and 15 can
have no errors in brightness.

[0060] FIG. 7 illustrates an example operation of displaying an image on a
display screen by updating consecutive image frames by scanning the rows
of sub-pixels using a selected one of multiple different scanning orders
for each frame and periodically changing the selection of scanning order.
In this example, the different scanning orders can be the first and
second scanning orders described above in reference to FIGS. 5 and 6. In
particular, FIG. 7 illustrates a scanning of the display using the first
scanning order for the update of the odd frames, and uses the second
scanning order for the updates of even frames. For the purposes of
illustration, FIG. 7 shows the characteristic decreases in brightness of
sub-pixels of block 2 that result from each of the particular scanning
orders. The patterns of decreases in brightness shown for block 2 in each
figure can be representative of the visual artifacts in the other blocks
of sub-pixels of the display. In the scanning method shown in FIG. 7,
frame 1 can be scanned using the first scanning order, which can result
in the decreases in brightness on sub-pixels 9, 11, 13, 15, and 16. In
the next frame, frame 2, the example scanning method can use the second
scanning order to scan the display, which can result in decreases in
brightness of sub-pixels 10, 12, 14, and 16. Scanning can continue by
repetitively alternating between the first and second scanning orders
every consecutive frame.

[0061] In this example scanning method, the pattern of decreased
brightness can change with each frame such that each sub-pixel can
alternate between two different amounts of brightness error from one
frame to the next. Rapidly alternating the two different amounts of error
in brightness can cause a visual effect of averaging the two different
amounts into an average brightness (luminance) error, as illustrated in
FIG. 7. For example, sub-pixel 9 can have an brightness error of a single
decrease in brightness in the scanning of the odd frames, and can have no
brightness error in the scanning of the even frames. Accordingly, an
average brightness error observed in sub-pixel 9 can be one-half (0.5) of
a decrease in brightness (compared to a single decrease in brightness
when the display is scanned using the first scanning order alone). FIG. 7
illustrates a one-half decrease in brightness with the notation of a
darker, thicker left border of sub-pixel 9 in the "Average Brightness
Error" column.

[0062] Sub-pixels 10-15 can each have a twice decrease in brightness using
one of the scanning orders, and no decrease in brightness using the other
scanning order. Thus, for each of sub-pixels 10-15, an average brightness
error resulting from scanning alternate frame using the first and second
scanning orders can be a single decrease in brightness, as shown in the
average brightness error column. Sub-pixel 16 can have a single decrease
in brightness in the odd frames, in which the first scanning order can be
used, and can have a twice decreased brightness in the even frames, in
which the second scanning order can be used. As a result, the average
brightness error that can be observable on sub-pixel 16 can be
one-and-a-half (1.5) decrease in brightness, which is represented in FIG.
7 with the notation of dark, thicker top, left, and bottom borders of the
sub-pixel.

[0063] Therefore, FIG. 7 shows that an average brightness error of
sub-pixel 9 can be a 0.5 decrease, sub-pixels 10-15 can be a single
decrease, and sub-pixel 16 can be a 1.5 decrease. Comparing the pattern
of the average brightness errors shown in FIG. 7 to the patterns of the
brightness errors using either of the first or second scanning orders
alone, it can be seen that the pattern of average brightness errors can
have greater uniformity of brightness errors across the sub-pixels of
block 2. In this way, for example, the appearance of display artifacts
can be mitigated by alternating the use of different scanning orders over
the scanning of multiple frames.

[0064] In some embodiments, the periodic changing of the selection of
scanning order can be less frequent than every consecutive image frame.
In other words, in some embodiments, multiple consecutive image frames
can be scanned using the same scanning order, and then the selection of
scanning order can be changed to a different scanning order.

[0065] In some embodiments, the selection of different scanning orders can
include more than two different scanning orders, and the periodic
changing of the selection of scanning order can occur with various
frequency and in various sequences of selected orders, as one skilled in
the art would understand, depending on the particular embodiment.

[0066] FIG. 8 illustrates another example operation of displaying an image
on a display screen by updating consecutive image frames by scanning the
rows of sub-pixels using a selected one of multiple different scanning
orders for each frame and periodically changing the selection of scanning
order. In this example, the different scanning orders can be a first
scanning order and a second scanning order. FIG. 8 illustrates a scanning
of the display using the first scanning order for the update of the odd
frames, and using the second scanning order for the updates of even
frames. The second scanning order in the example of FIG. 8 can be the
same second scanning order as described above in reference to FIG. 6.
That is, the second scanning order can include a reordered 4-line
inversion scheme in which each block can be scanned in the following line
order of rows in the block: second row, fourth row, sixth row, eighth
row, first row, third row, fifth row, seventh row (2nd, 4th, 6th, 8th,
1st, 3rd, 5th, 7th). FIG. 8 shows a set of multiple adjacent blocks
(e.g., block 1, block 2, block 3, etc.) of the display can be scanned
with the second scanning order. Block 1 can include rows 1-8, block 2 can
include rows 9-16, etc.

[0067] The first scanning order in the example of FIG. 8 can include a
reordered 4-line inversion scheme in which each block can be scanned in
the same line order as the line order of rows in the block used by the
second scanning order (i.e., rows 2, 4, 6, 8, 1, 3, 5, and 7). However,
the first scanning order can scan a different set of multiple adjacent
blocks than scanned by the second scanning order. For example, in the
first scanning order, block 1 can include rows 1-3, block 2 can include
rows 4-11, block 3 can include rows 12-19, etc. In other words, the first
scanning order can scan a first set of adjacent blocks, and the second
scanning order can scan a second set of adjacent blocks such that each
block in the second set is shifted by a particular number of rows (i.e.,
five rows in this example) from a corresponding block in the first set.
For example, FIG. 8 shows that block 2 in the first scanning order begins
at row 4, and block 2 in the second scanning order begins at row 9.

[0068] For the purposes of illustration, FIG. 8 shows the characteristic
decreases in brightness of sub-pixels that result from each of the
particular scanning orders. The patterns of decreases in brightness shown
for the first and second scanning orders can be representative of the
visual artifacts in the other blocks of sub-pixels of the display. In the
scanning method shown in FIG. 8, the odd frames can be scanned using the
first scanning order, which can result in a single decrease in brightness
of sub-pixel 1 and a twice decrease in brightness of the remaining odd
sub-pixels, i.e., sub-pixels 3, 5, 7, 9, etc. The even frames can be
scanned using the second scanning order, which can result in a twice
decrease in brightness of the even sub-pixels, i.e., sub-pixels 2, 4, 6,
8, etc. Thus, scanning in this example can repetitively alternate between
the first and second scanning orders every consecutive frame.

[0069] FIG. 8 shows an average luminance that can be observed due to the
rapid alternating between the two patterns of brightness errors caused by
the first and second scanning orders. In the average luminance, row 1 can
have a 0.5 decrease in brightness and the remaining rows can have a
single decrease in brightness. As a result, for example, the appearance
of display artifacts can be mitigated by alternating the use of different
scanning orders over the scanning of multiple frames.

[0070] FIG. 9 illustrates another example operation of displaying an image
on a display screen by updating consecutive image frames by scanning the
rows of sub-pixels using a selected one of multiple different scanning
orders for each frame and periodically changing the selection of scanning
order. In this example, eight different scanning orders can be used. FIG.
8 illustrates a scanning of the display by updating eight consecutive
image frames with eight different scanning orders. In particular, a first
scanning order can be selected and used to update the first frame, a
second scanning order can be selected and used to update the second
frame, a third scanning order can be selected and used to update the
third frame, etc. In each scanning order in this example, the reordered
4-line inversion scheme described above with respect to FIGS. 6 and 8 can
be used. Each scanning order in the example of FIG. 9 can use the same
line order within each block as the line order used by the second
scanning order described above. Accordingly, each scanning order can scan
the blocks with the following line order of rows in the block: second
row, fourth row, sixth row, eighth row, first row, third row, fifth row,
seventh row (2nd, 4th, 6th, 8th, 1st, 3rd, 5th, 7th). For the purpose of
clarity, FIG. 9 shows only a single representative block of eight rows
for each scanning order.

[0071] As FIG. 9 illustrates, the blocks in each consecutive scanning
order can be shifted by one row. In the first scanning order, the block
can include rows 1-8, in the second scanning order, the block can include
rows 2-9, in the third scanning order, the block can include rows 3-10,
etc. For the purposes of illustration, FIG. 9 shows the characteristic
decreases in brightness of sub-pixels that result from each of the
particular scanning orders. The patterns of decreases in brightness shown
for the first through eighth scanning orders can be representative of the
visual artifacts in the other blocks of sub-pixels of the display. In the
scanning method shown in FIG. 9, the decreases in brightness can be
changed across multiple frames, so that the perception of visual
artifacts can be reduced or eliminated.

[0072] Although the foregoing example embodiments describe one example
visual artifact, i.e., reduced brightness due to voltage changes on
aggressor sub-pixels affecting voltages on victim sub-pixels, one skilled
in the art would understand that other types of visual artifacts may be
reduced or eliminated using some embodiments. For the purpose of
illustration, another example visual artifact will now be described with
reference to FIG. 10.

[0073] FIG. 10 illustrates some details of example display screen 1050.
FIG. 10 includes a magnified view of display screen 1050 that shows
multiple display pixels 1053, each of which can include multiple display
sub-pixels, such as red (R), green (G), and blue (B) sub-pixels in an RGB
display. Data lines 1055 can run vertically through display screen 1050,
such that each display pixel in a column of display pixels can include a
set 1056 of three data lines (an R data line 1055a, a G data line 1055b,
and a B data line 1055c) corresponding to the three sub-pixels of each
display pixel.

[0074] In this example, the data lines that correspond to multiple
sub-pixels of a display pixel, such as R data line 1055a, G data line
1055b, and B data line 1055c in FIG. 10, can be operated sequentially
during an update of the pixel. For example, a display driver or host
video driver (not shown) can multiplex an R data voltage, a G data
voltage, and a B data voltage onto a single data voltage bus line 1058 in
a particular sequence, and then a demultiplexer 1061 in the border region
of the display can demultiplex the R, G, and B data voltages to apply the
data voltages to data lines 1055a, 1055b, and 1055c in the particular
sequence. Each demultiplexer 1061 can include three switches 1063 that
can open and close according to the particular sequence of sub-pixel
charging for the display pixel. In an R-G-B sequence, for example, data
voltages can be multiplexed onto data voltage bus line 1058 such that R
data voltage is applied to R data line 1055a during a first time period,
G data voltage is applied to G data line 1055b during a second time
period, and B data voltage is applied to B data line 1055c during a third
time period. Demultiplexer 1061 can demultiplex the data voltages in the
particular sequence by closing switch 1063 associated with R data line
1055a during the first time period when R data voltage is being applied
to data voltage bus line 1058, while keeping the green and blue switches
open such that G data line 1055b and B data line 1055c are at a floating
potential during the application of the R data voltage to the R data
line. In this way, for example, the red data voltage can be applied to
the pixel electrode of the red sub-pixel during the first time period.
During the second time period, when G data voltage is being applied to G
data line 1055b, demultiplexer 1061 can open the red switch 1063, close
the green switch 1063, and keep the blue switch 1063 open, thus applying
the G data voltage to the G data line, while the R data line and B data
line are floating. Likewise, the B data voltage can be applied during the
third time period, while the G data line and the R data line are
floating.

[0075] While applying a voltage to the data line of a particular sub-pixel
can charge the sub-pixel (e.g., the pixel electrode of the sub-pixel) to
the voltage level of the applied voltage, applying a voltage to one data
line can affect the voltage on floating data lines, for example, because
a capacitance existing between data lines can allow voltage changes on
one data line to be coupled to other data lines. This capacitive coupling
can change the voltage on the floating data lines, which can make the
sub-pixels corresponding to the floating data lines appear either
brighter or darker depending on whether the voltage change on the
charging data line is in the same direction or opposite direction,
respectively, as the polarity of the floating data line voltage. In
addition, the amount of voltage change on the floating data line can
depend on the amount of the voltage change on the charging data line.

[0076] By way of example, a negative data voltage, e.g., -2V, may be
applied to data line A during the scan of a first line. Then, during the
scan of the next line, a positive data voltage, e.g., +2V, may be applied
to data line A, thus swinging the voltage on data line A from -2V to +2V,
i.e., a positive voltage change of +4V. Voltages on floating data lines
surrounding data line A can be increased by this positive voltage swing.
For example, the positive swing on data line A can increase the voltage
of an adjacent data line B floating at a positive voltage, thus,
increasing the magnitude of the positive floating voltage and making the
sub-pixel corresponding to data line B appear brighter. Likewise, the
positive voltage swing on data line A can increase the voltage of an
adjacent data line C floating at a negative voltage, thus, decreasing the
magnitude of the negative floating voltage and making the sub-pixel
corresponding to sub-pixel C appear darker. Thus, the appearance of
visual artifacts of brighter or darker sub-pixels can depend on, for
example, the occurrence of large voltage changes on one or more data
lines during scanning of a display and the polarity of surrounding data
lines with floating voltages during the large voltage changes.

[0077] In addition, the appearance of visual artifacts can depend on the
particular sequence in which the data voltages are applied. Further to
the example above, after a data voltage is applied to data line A, a data
voltage may be applied to data line B (data line B being next in
sequence). In this case, the effect of the voltage swing on data line A,
i.e., the increase in the voltage on data line B, can be "overwritten" by
the subsequent charging of data line B.

[0078] While the particular sequence in which the data voltages are
applied to a set of data lines can be independent of the type of
inversion scheme, the occurrence of large voltage changes in data lines,
and the polarities of the floating voltages on adjacent data lines during
the large voltage changes, can each depend on the type of inversion
scheme used to operate the display. In one example, visual artifacts can
occur using scanning orders such as the first through eighth scanning
orders of the example scanning operation described above with reference
to FIG. 9, i.e., a reordered 4-line inversion scheme using a line order
of rows 2, 4, 6, 8, 1, 3, 5, and 7 (in which rows 2, 4, 6, and 8 can be
updated using voltages of the same polarity, and rows 1, 3, 5, and 7 can
be updated using voltages of the opposite polarity as the voltages
applied to rows 2, 4, 6, and 8). In particular, in this example scanning
operation, visual artifacts that can result from coupling of voltage
changes between data lines can result in erroneous increases in
brightness of the sub-pixels in the first two rows of each block.

[0079] In addition, it is noted that it may also be possible to use one
fixed scanning order that can result in errors in brightness that are not
detectable as visual artifacts. In one example, the scanning order used
in the example of FIG. 8 shows different scanning orders for odd and even
frames. In some cases, it may be possible that the pattern of errors
illustrated in the figure for the odd frame scanning order could be
undetectable because of the high spatial frequency of the resulting
errors in the pattern. Likewise, the error pattern shown for the even
frame scanning order might not be detectable. On the other hand, the
scanning order of the example of FIG. 5 might result in visible
artifacts, for example, because the errors resulting from this scanning
order can occur at a lower spatial frequency.

[0080] FIG. 11 illustrates the example scanning operation that is
illustrated in FIG. 9. However, in addition to the errors that can result
from coupling of voltage changes between pixel electrodes of the
sub-pixels, FIG. 11 shows errors that can result from another error
mechanism, i.e., from coupling of voltage changes between data lines. In
particular, FIG. 11 illustrates an erroneous increase in brightness in
each of the first two sub-pixels in each block with the dash marks
surrounding each of the first two sub-pixels in each block.

[0081] As FIG. 11 illustrates, the example scanning operation described
above in reference to FIG. 9 can be used to change the position of visual
artifacts that can result from data line to data line coupling of voltage
changes. In this way, the persistence of these visual artifacts at a
particular position may be disrupted across multiple image frames, and as
a result, these visual artifacts may be imperceptible or less
perceptible.

[0082] Although embodiments of this disclosure have been fully described
with reference to the accompanying drawings, it is to be noted that
various changes and modifications including, but not limited to,
combining features of different embodiments, omitting a feature or
features, etc., as will be apparent to those skilled in the art in light
of the present description and figures.

[0083] For example, one or more of the functions of displaying an image on
a display described above can be performed by computer-executable
instructions, such as software/firmware, residing in a medium, such as a
memory, that can be executed by a processor, as one skilled in the art
would understand. The software/firmware can be stored and/or transported
within any computer-readable medium for use by or in connection with an
instruction execution system, apparatus, or device, such as a
computer-based system, processor-containing system, or other system that
can fetch the instructions from the instruction execution system,
apparatus, or device and execute the instructions. In the context of this
document, a "non-transitory computer-readable storage medium" can be any
physical medium that can contain or store the program for use by or in
connection with the instruction execution system, apparatus, or device.
The non-transitory computer-readable storage medium can include, but is
not limited to, an electronic, magnetic, optical, electromagnetic,
infrared, or semiconductor system, apparatus or device, a portable
computer diskette (magnetic), a random access memory (RAM) (magnetic), a
read-only memory (ROM) (magnetic), an erasable programmable read-only
memory (EPROM) (magnetic), a portable optical disc such a CD, CD-R,
CD-RW, DVD, DVD-R, or DVD-RW, or flash memory such as compact flash
cards, secured digital cards, USB memory devices, memory sticks, and the
like. In the context of this document, a "non-transitory
computer-readable storage medium" does not include signals. In contrast,
in the context of this document, a "computer-readable medium" can include
all of the media described above, and can also include signals.

[0084] FIG. 12 is a block diagram of an example computing system 1200 that
illustrates one implementation of an example scanning system of a display
screen according to embodiments of the disclosure. In the example of FIG.
12, the computing system is a touch sensing system 1200 and the display
screen is a touch screen 1220, although it should be understood that the
touch sensing system is merely one example of a computing system, and
that the touch screen is merely one example of a type of display screen.
Computing system 1200 could be included in, for example, mobile telephone
136, digital media player 140, personal computer 144, or any mobile or
non-mobile computing device that includes a touch screen. Computing
system 1200 can include a touch sensing system including one or more
touch processors 1202, peripherals 1204, a touch controller 1206, and
touch sensing circuitry (described in more detail below). Peripherals
1204 can include, but are not limited to, random access memory (RAM) or
other types of memory or non-transitory computer-readable storage media
capable of storing program instructions executable by the touch processor
1202, watchdog timers and the like. Touch controller 1206 can include,
but is not limited to, one or more sense channels 1208, channel scan
logic 1210 and driver logic 1214. Channel scan logic 1210 can access RAM
1212, autonomously read data from the sense channels and provide control
for the sense channels. In addition, channel scan logic 1210 can control
driver logic 1214 to generate stimulation signals 1216 at various
frequencies and phases that can be selectively applied to drive regions
of the touch sensing circuitry of touch screen 1220. In some embodiments,
touch controller 1206, touch processor 1202 and peripherals 1204 can be
integrated into a single application specific integrated circuit (ASIC).
A processor, such as touch processor 1202, executing instructions stored
in non-transitory computer-readable storage media found in peripherals
1204 or RAM 1212, can control touch sensing and processing, for example.

[0085] Computing system 1200 can also include a host processor 1228 for
receiving outputs from touch processor 1202 and performing actions based
on the outputs. For example, host processor 1228 can be connected to
program storage 1232 and a display controller, such as an LCD driver
1234. Host processor 1228 can use LCD driver 1234 to generate an image on
touch screen 1220, such as an image of a user interface (UI), by
executing instructions stored in non-transitory computer-readable storage
media found in program storage 1232, for example, to scan lines (e.g.,
rows) of sub-pixels of touch screen 1220 by applying voltages to pixel
electrodes of adjacent sub-pixels in different lines such that polarity
changes in opposite directions can occur in two sub-pixels that are
adjacent to a particular sub-pixel. In other words, host processor 1228
and LCD driver 1234 can operate as a scanning system in accordance with
the foregoing example embodiments. In some embodiments the touch
processor 1202, touch controller 1206, or host processor 1228 may
independently or cooperatively operate as a scanning system in accordance
with the foregoing example embodiments. Host processor 1228 can use touch
processor 1202 and touch controller 1206 to detect and process a touch on
or near touch screen 1220, such a touch input to the displayed UI. The
touch input can be used by computer programs stored in program storage
1232 to perform actions that can include, but are not limited to, moving
an object such as a cursor or pointer, scrolling or panning, adjusting
control settings, opening a file or document, viewing a menu, making a
selection, executing instructions, operating a peripheral device
connected to the host device, answering a telephone call, placing a
telephone call, terminating a telephone call, changing the volume or
audio settings, storing information related to telephone communications
such as addresses, frequently dialed numbers, received calls, missed
calls, logging onto a computer or a computer network, permitting
authorized individuals access to restricted areas of the computer or
computer network, loading a user profile associated with a user's
preferred arrangement of the computer desktop, permitting access to web
content, launching a particular program, encrypting or decoding a
message, and/or the like. Host processor 1228 can also perform additional
functions that may not be related to touch processing.

[0086] Touch screen 1220 can include touch sensing circuitry that can
include a capacitive sensing medium having a plurality of drive lines
1222 and a plurality of sense lines 1223. It should be noted that the
term "lines" is sometimes used herein to mean simply conductive pathways,
as one skilled in the art will readily understand, and is not limited to
elements that are strictly linear, but includes pathways that change
direction, and includes pathways of different size, shape, materials,
etc. Drive lines 1222 can be driven by stimulation signals 1216 from
driver logic 1214 through a drive interface 1224, and resulting sense
signals 1217 generated in sense lines 1223 can be transmitted through a
sense interface 1225 to sense channels 1208 (also referred to as an event
detection and demodulation circuit) in touch controller 1206. In this
way, drive lines and sense lines can be part of the touch sensing
circuitry that can interact to form capacitive sensing nodes, which can
be thought of as touch picture elements (touch pixels), such as touch
pixels 1226 and 1227. This way of understanding can be particularly
useful when touch screen 1220 is viewed as capturing an "image" of touch.
In other words, after touch controller 1206 has determined whether a
touch has been detected at each touch pixel in the touch screen, the
pattern of touch pixels in the touch screen at which a touch occurred can
be thought of as an "image" of touch (e.g. a pattern of fingers touching
the touch screen).

[0087] In some example embodiments, touch screen 1220 can be an integrated
touch screen in which touch sensing circuit elements of the touch sensing
system can be integrated into the display pixels stackups of a display.

[0088] Although various embodiments are described with respect to display
pixels, one skilled in the art would understand that the term display
pixels can be used interchangeably with the term display sub-pixels in
embodiments in which display pixels are divided into sub-pixels. For
example, some embodiments directed to RGB displays can include display
pixels divided into red, green, and blue sub-pixels. One skilled in the
art would understand that other types of display screen could be used.
For example, in some embodiments, a sub-pixel may be based on other
colors of light or other wavelengths of electromagnetic radiation (e.g.,
infrared) or may be based on a monochromatic configuration, in which each
structure shown in the figures as a sub-pixel can be a pixel of a single
color.